In a bid to evolve past the age of cookie placement, marketers are gradually moving towards a process called fingerprinting, whereby a unique image of a computer is acquired by monitoring its characteristics – plugins, software, screen size, fonts, and the like. This creates a unique pattern, comparable to that of a fingerprint.

Studies by the Electronic Frontier Foundation estimate that 94 per cent of browsers that use Flash or Java have unique identities.

For the online advertiser, this presents a more enduring tracking option, since a user’s fingerprint persists even if they remove their cookies, and protective changes to software and settings in fact make users more identifiable to advertisers.

Though some advertisers are reluctant to talk about their work with fingerprinting technology, for fear of public outcry, one company called Adstack is open about its wares. The San Francisco startup’s technology allows firms to send an email where the content is only delivered when the user opens it. This means the advertiser can alter the content up to the millisecond, delivering personalised messages timed to precision.